Reading your post made me wonder if they'll just keep Standard on Arena and not worry about other formats. Standard is where Wizards makes their money, does it make sense for them to promote other formats with cards that aren't yet available on Arena?
One option would be to give Arena a year or two, then create a new format that only includes cards from Arena's inception and have that be their new format. So all of those non-Standard legal cards would have a use and they would still be promoting Standard.
If Arena reaches Hearthstone heights, I think Wizards would be very pleased.
What does all of this mean for paper Magic? Is it on the outs?

I'm thinking of selling off the majority of my paper collection, too. Like you, thinking about saving a few decks because the collection is just too much stuff. Feeling a little overwhelmed with it all and I'll never use 95% of this stuff.
I will keep a couple of sets for nostalgia, but the rest will probably be sold off. Just trying to decide how to sell it off.

Mentioned in the thread @Affinity for MTG posted about his deck being so cheap on MTGO, but I feel bad for the people who have tons of money invested in MTGO. If the intention is to eventually shut MTGO down, how would they roll over that money to a new system? Is it all just going to disappear? I know Arena can't do as many formats (yet) as MTGO, but eventually I assume it's going to include every format.
As far as the professional stuff goes, not sure if it's good or bad. I don't keep up with the pro players or events for the most part.

Just a quick update on the site and it's new resources. In November we were really close to exceeding CPU usage and having site downtime. I guess this is kind of a good news/bad news situation.
As a result, I've uninstalled some mods that weren't being used and started restricting certain features to users who aren't active, namely RSS feeds. Just mentioning this as you'll notice a few things are gone or different. Nothing major, but just a heads up

Do any of you use Sony Vegas? I have version 12 and started playing around with it, looking for a couple of helpful tips. Was trying to trip a portion of the video and ended up watching YouTube videos for half an hour and putzing around for another half an hour trying to figure it out

I was listening to the last episode of @MTGZuby and the discussion went into cheating at pre-releases. I've never been to a pre-release, but I've heard from a few people that cheating is rampant.
In your opinion, where is cheating most prevalent? Certain formats at your LGS? Or even just casually with friends?

That's a good question. If you were to cast Phytoburst first, then Deepglow Skate it would double the total. But at the end of the turn, I'm not sure how many of those +5's come off or if it's 10 counters.